Retractable stop for low overhead elevators

ABSTRACT

A retractable stop and the method of use thereof to control travel range of an elevator system are disclosed. The retractable stop may include a vertical mounting bracket, an impact plate, and a support member. The support member may include an upper end pivotably connected to a distal portion of the impact plate and a lower end movable in relation to the mounting bracket. The proximal portion of the impact plate may be pivotably connected to the mounting bracket. When the retractable stop is in a retracted position, the impact plate does not significantly contribute to the lateral profile of the retractable stop.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national stage filing under 35 USC §371 ofInternational Patent Application No. PCT/IB2010/001056, filed on Apr.12, 2010.

FIELD OF THE DISCLOSURE Background

This disclosure generally relates to elevators and more particularlyrelates to retractable stop for controlling the travel range of anelevator system during normal or maintenance operation.

BACKGROUND OF THE DISCLOSURE

Low overhead elevators have become increasingly popular. As opposed totraditional elevators which include motors, governors, and associatedcabling in a machine room at the top of vertical hoistways in which theelevators move, low overhead elevators do not require placement of suchcomponents at the top of the hoistways. For example, some low overheadelevators may provide the driving force through machines located abovethe elevator roof but without the provision of a machine room. In sodoing, such low overhead elevators conserve valuable space in thecommercial and residential buildings in which they operate.

When a service technician wants to inspect or service the pulleys,hoisting cables, guide rails, machine controls or any other device atthe upper end of the hoistway, he or she usually needs to do so on topof an elevator car. The cars may be designed to slowly approach thedesired locations, such as by using a control system as disclosed in aco-pending application published as WO 2008/004022. In order to maintainthe safety of the technician, extra preventive measures have beendeveloped to stop the upward movement of the car as it approaches thetop of the hoistway to provide ample space for the technician. This isparticularly important in the case of low overhead elevators, in whichthere is less clearance between the top of car and the top of thehoistway.

One of the preventative measures is a retractable stop provided at thepit floor of the elevator system to block further downward movement of acounterweight when deployed. An example of this is disclosed in anotherco-pending application published as WO 2008/002300. As the counterweightis operatively connected to the elevator car, stopping downward movementof the counterweight necessarily stops upward movement of the car. Whenthe elevator operates under normal mode, the stop is retracted to allowthe counterweight to downwardly extend to its full range.

When deployed, a triangular support structure is formed among ahorizontal strike plate, an oblique stop member and a vertical mountingchannel, in which the horizontal impact plate blocks the downwardmovement of the counterweight with the impact force transmitted into thepit floor through the mounting channel and support member. However, thetriangular configuration necessarily requires the support member to bearsome horizontal vector of the impact force. As a result, the supportmember has to be constructed with sufficient lateral dimension and heftto provide the needed structural rigidity.

Meanwhile, the dimensions and location of the elevator car andcounterweight are restricted by the limited space within the hoistway.In order to maintain safe operation of the elevator car in its fullrange, a minimum clearance (e.g. 25 mm) is required between the fullyretracted stop and counterweight to accommodate any incidentalhorizontal movement of the counterweight within the hoistway. However,because of its relatively thick lateral profile necessary to maintainadequate structural rigidity, the existing stop may fail to meet theminimum clearance requirement. One solution is to create a longitudinalgroove on the surface of the counterweight (including the counterweightframe and counterweight filler) that faces the retractable stop toprovide the extra clearance. While effective, this necessarily requiresmodification of the existing elevator system or creation of aspecifically configured counterweight, either of which adds significantexpense to the design.

Hence, there is a need for a retractable stop with an improved lateralprofile that meets the minimum clearance requirement when used with aconventional counterweight without imparting significant additionalcost. Moreover, there is a need for a retractable stop that has animproved lateral profile in a retracted position without sacrificing theload bearing capacity in a deployed position.

SUMMARY OF THE DISCLOSURE

In satisfaction of the aforementioned needs, a retractable stop and themethod of use thereof to control travel range of an elevator system aredisclosed. The retractable stop may include a vertical mounting bracket,an impact plate, and a support member. The support member may include anupper end pivotably connected to the distal portion of the impact plateand a lower end movable in relation to the mounting bracket.

In another aspect of this disclosure, a method of using the disclosedretractable stop to control travel range of an elevator assemblycomprising an elevator counterweight having a vertical trajectory isdisclosed. The method may include the steps of providing a retractablestop, the stop comprising an impact plate and a support member having anupper end pivotably connected to the impact plate; and extending thestop into a deployed position in which the impact plate is at leastsubstantially horizontal and within the vertical trajectory of thecounterweight and in which the support member is at least substantiallyvertical.

Other advantages and features of the disclosed retractable stop andmethod of use thereof will be described in greater detail below. It willalso be noted here and elsewhere that the device or method disclosedherein may be suitably modified to be used in a wide variety ofapplications by one of ordinary skill in the art without undueexperimentation.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the disclosed device and method,reference should be made to the embodiments illustrated in greaterdetail in the accompanying drawings, wherein:

FIG. 1 is a schematic illustration of a prior art elevator system usingan existing retractable stop, depicted in a deployed position;

FIG. 2 is a schematic illustration of the prior art elevator system withthe retractable stop, depicted in a retracted position;

FIG. 3 is a partial top view of the prior art elevator system in FIG. 2,particularly illustrating the lateral profile of the stop necessitatinga surface groove on the counterweight to meet the minimum clearancerequirement;

FIG. 4 is a front exploded view of one embodiment of a stop constructedin accordance with this disclosure;

FIG. 5 is a back exploded view of the stop illustrated in FIG. 4;

FIG. 6 is a back perspective view of the stop shown in FIGS. 4-5 anddepicted in a deployed position;

FIG. 7 is a side view of the stop illustrated in FIG. 6;

FIG. 8 is an front perspective view of the stop illustrated in FIGS. 4-5and depicted in a retracted position;

FIG. 9 is an side view of the stop illustrated in FIG. 8;

FIG. 10 is a partial top view of the stop illustrated in FIGS. 4-9,particularly illustrating the retractable locking pin;

FIG. 11 is a partial top view of an elevator system using the stopillustrated in FIGS. 8-9, particularly illustrating the improved lateralprofile of the disclosed stop and depicted in the retracted position;and

FIG. 12 is a block diagram of a method of controlling travel range of anelevator assembly according to another aspect of this disclosure.

It should be understood that the drawings are not necessarily to scaleand that the disclosed embodiments are sometimes illustrateddiagrammatically and in partial views. In certain instances, detailswhich are not necessary for an understanding of the disclosed device ormethod which render other details difficult to perceive may have beenomitted. It should be understood, of course, that this disclosure is notlimited to the particular embodiments illustrated herein.

DETAILED DESCRIPTION OF THE DISCLOSURE

This disclosure is generally directed to a safety device that maintainsa desired amount of overhead clearance for a service technicianoperating on top of an elevator car in a hoistway. In particular, thedevice is a retractable stop that prevents further downward movement ofa counterweight when deployed, thereby ensuring that the correspondingelevator car will not move above a selected height within the hoistway.As the device is generally mounted on a stationary vertical surface(e.g. a car guide) of an elevator system, “proximal” is used in thisdisclosure to refer to a direction toward the vertical surface while“distal” is used to refer to a direction away from the vertical surface.

A prior art retractable stop with a triangular configuration isschematically illustrated in FIGS. 1-3. The triangular stop 10 includesa mounting channel 11 mounted on a car guide, a stop member 12 having alower end pivotably connected to a lower end of the mounting channel 11,and a strike plate 13 having a proximal portion 16 slidably coupled tothe car guide and a distal portion 17 pivotably connected to an upperend 14 of the stop member 12.

In a deployed position as illustrated in FIG. 1, the stop member 12pivots away from the mounting channel 11, causing the distal portion 17of the strike plate 13 to slide downwardly along the car guide until itrests on an upper end 18 of the mounting channel 11, forming atriangular support structure that blocks the vertical trajectory of acounterweight 19. Because the counterweight 19 is operatively connectedto an elevator car 15, blocking downward movement of the counterweight19 stops upward movement of the elevator car 15.

In a retracted position as illustrated in FIG. 2, the stop member 12pivots toward the mounting channel 11, causing the proximal portion 16of the strike plate 13 to slide upwardly along the car guide until thestop member 12 is in a substantially vertical position. In the retractedposition, the stop 10 is clear of the vertical trajectory of thecounterweight 19, thereby allowing movement of the elevator car 15 inits full range.

However, because of the lateral vector inherent to the triangular stop10, the stop member 12 needs to be of a sufficient thickness andrigidity to sustain the impact force of the counterweight 19 when thestop 10 is deployed. Moreover, because of the sliding engagement of thestrike plate 13 with the car guide, the strike plate 13 cannot be foldedinto a substantially or completely vertical position when the stop isretracted, which, in combination with the thickness of the stop member,may result in a lateral profile that cannot meet the minimum clearancerequirement (e.g. 25 mm) between the stop and a conventionalcounterweight, as discussed earlier in this disclosure. One solution isto modify the counterweight 19 to include a vertical groove 19 a asillustrated in FIG. 3, which may be economically undesirable and/ortechnologically challenging.

To address the aforementioned problem, the retractable stop disclosedherein has an improved lateral profile that meets the minimum clearancerequirement without sacrificing its structural rigidity. In theembodiment disclosed in FIGS. 4-9, the disclosed stop 20 may include amounting bracket 21 adapted to be secured to a stationary surface withinthe hoistway 27 of an elevator system. In this embodiment (as shown inparticular in FIG. 6), the mounting bracket 21 is secured to a car guide22 (which guides vertical movement of the elevator car) by a pluralityof fasteners 23. However, the mounting bracket 21 may also be secured toa counterweight guide, a hoistway wall, a pit floor, or other suitablesurfaces so long as the location of the stop 20 allows it to block thevertical trajectory of the counterweight when the stop 20 is deployed.The mounting bracket 21 may include upper and lower portions (24, 25).The lower portion 25 of the mounting bracket 21 may be indirectlycoupled to a pit floor 26 of the hoistway 27 through a support plate(not shown) to reduce or prevent impact damage to the pit floor 26, orit may be in direct contact with the pit floor 26 if such damage isminimal or can be reduced by other designs.

The disclosed stop 20 may further include an impact plate 30 havingproximal and distal portions (31, 32). The proximal portion 31 of theimpact plate 30 may be pivotably connected to the upper portion 24 ofthe mounting bracket 21, such as through two rivets (33, 34) or thelike. In an alternative embodiment (not shown), the proximal portion 31of the impact plate 30 may also be slidably coupled to the car guide 22(e.g. the configuration disclosed in WO 2008/002300). In any event, theimpact plate 30 is pivotable from a retracted position (FIGS. 8-9) inwhich the impact plate 30 is at least substantially vertical, to adeployed position (FIGS. 6-7) in which the impact plate 30 is at leastsubstantially horizontal. The dimension and shape of the impact plate 30should allow the distal portion 32 of the impact plate 30 to at leastpartially protrude into the vertical trajectory of the counterweightwhen the stop 20 is deployed, and is not limited to the specificembodiment shown in FIGS. 4-9. In this disclosure, “substantiallyvertical” or “substantially horizontal” refers to an orientation that iswithin 10°, 5°, or even 3° of the vertical or horizontal orientation.

As another load-bearing component, the stop 20 may include a supportmember 40 having upper and lower ends (41, 42). The upper end 41 of thesupport member 40 is pivotably connected to the distal portion 32 of theimpact plate 30, such as through two rivets (43, 44) or the like. Unlikethe prior art triangular stop 10 illustrated in FIGS. 1-2, the lower end42 of the support member 40 may be translationally movable in relationto the mounting bracket 21. In particular, the lower end 42 ishorizontally extendable as the support member 40 moves from a retractedposition (FIGS. 8-9), in which the support member 40 is closer to (or inthis embodiment partially recessed within) the mounting bracket 21, to adeployed position (FIGS. 6-7), in which the support member 40 distallyextends away from the mounting bracket 21. The support member 40,however, remains at least substantially vertical in both positions. Likethe lower portion of the mounting bracket 21, the lower end 42 of thesupport member 40 in the deployed position may be indirectly coupled tothe pit floor 26 of the hoistway 27 through a support plate (not shown)to reduce or prevent impact damage to the pit floor 26, or it may be indirect contact with the pit floor 26 if such damage is minimal or can bereduced by other designs. The support plates for the support member 40and mounting bracket 21 may be a one-piece or separated design.

Finally, the disclosed stop 20 may further include an optional crossmember 50 that interconnects the mounting bracket 21 and support member40 for structural rigidity purposes. The cross member 50 may also assistthe movement of the support member 40 between the retracted and deployedpositions. As illustrated in FIGS. 4-5, the cross member 50 may alsoinclude proximal and distal portions (51, 52). The proximal portion 51of the cross member 50 is pivotably connected to the mounting bracket 21through rivets (53, 54) or the like, while the distal portion 52 may bepivotably connected to the support member 40 through rivets (55, 56) orthe like. The cross member 50 may be of a single-piece construction orit may include two side bars as shown in FIGS. 4-5. Besides improvingstructural rigidity of the disclosed stop 20, the cross member 50 mayalso facilitate the transition of the stop 20 between the deployed andretracted positions, which is discussed in greater detail below.

When the stop 20 is deployed as illustrated in FIGS. 6-7, the crossmember 50 is pivoted away from the mounting bracket 21 until it is in anat least substantially horizontal position, thereby extending thesupport member 40 distally away from the mounting bracket 21. To retractthe stop 20, the cross member 50 is pivoted toward the mounting bracket21 until it is in an at least substantially vertical position asillustrated in FIGS. 8-9, thereby moving the support member 40proximally toward the mounting bracket 21. However, the stop 20 may alsobe deployed and/or retracted without the assistance of the cross member50, such as by simply pushing or pulling the support member 40 orpivoting the impact plate 30.

As illustrated in FIGS. 4-9, the mounting bracket 21 may further includean optional holding member 60 that releasably couples the mountingbracket 21 and support member 40 together when the stop 20 is in theretracted position. Turning to FIG. 10, the holding member 60 mayinclude a retractable locking pin 61 operatively coupled to an actuator62, such as a solenoid coil that controls the position of the pin 61.When the stop 20 is in the retracted position, the pin 61 protrudes intoat least one receiving area 63 provided on the support member 40,thereby holding the support member 40 close to the mounting bracket 21.To deploy the stop 20, the pin 61 is retracted by the actuator 62,thereby releasing the support member 40 from the mounting bracket 21.Although the receiving area 63 is shown in FIGS. 4-5 as a side opening,it may alternatively be a recess provided on the surface of the supportmember 40. Likewise, the locations of the holding member 60 andreceiving area 63 are not limited to the embodiments disclosed herein.Finally, instead of being electronically actuated by the solenoid coil,the retractable pin 61 may be mechanically actuated, such as throughhydraulic actuators, or even manually actuated.

One feature of the disclosed stop 20 is that the vertical orientation ofthe support member 40, in contrast to the oblique orientation in theprior art triangular stop 10, at least substantially reduces oreliminates the horizontal vector of the impact force caused by thecounterweight when the stop 20 is deployed. As a result, the overalllateral profile of the support member 40 and the stop 20 may be reducedwhile maintaining the required structural rigidity. Another optionalfeature of the disclosed stop 20 is that the proximal portion 31 of theimpact plate 30 is pivotably connected to the mounting bracket 21, whichallows the impact plate 30 to be at least substantially vertical whenthe stop 20 is retracted, thereby reducing or even eliminating itscontribution to the overall lateral profile of the stop 20. Asillustrated in FIG. 11, the disclosed stop 20 with a reduced lateralprofile meets the minimum clearance requirement (e.g. 25 mm) without anymodification (e.g. vertical surface grooves) to the counterweight 29.

In some embodiments, the stop 20 may further include an indicator (notshown) that signals the current position of the stop 20 to a servicetechnician. The indicator may be visual (e.g. green and red lightspositioned on the elevator roof to indicate the deployed and retractedpositions of the stop, respectively) and/or audio (e.g. a series ofbeeps). Alternatively, the indicator may be electronic and include atransmitter than sends signals to a receiver that is accessible to theservice technician.

For example, the receiver may be integrated into a control panelpositioned on top of the elevator car. The control panel may furtherinclude at least one switch that remotely controls the operation of thestop 20, such as by remotely manipulating the actuator 62 to release thestop 20 from the retracted position to the deployed position. Thecontrol panel may also include a module that controls the movement ofthe elevator car running under maintenance mode. In light of thisdisclosure, those skilled in the art would be able to select from amongknown components and to arrange wire-based or wireless communicationsbetween the stop 20 and the service technician to achieve the desiredcontrol of the position of the stop 20 between the normal andmaintenance operation modes of the elevator car.

In another aspect of this disclosure illustrated in FIG. 12, a method ofcontrolling travel range of an elevator counterweight having a verticaltrajectory is disclosed. The method 100 may include the steps of:providing a retractable stop, the stop comprising an impact plate and asupport member having an upper end pivotably connected to the impactplate and a lower end movable in relation to the car guide (101);extending the stop into a deployed position in which the support memberremains at least substantially vertical while the impact plate is atleast substantially horizontal and at least partially blocking thevertical trajectory of the counterweight (102); and folding the stopinto a retracted position in which the impact plate is at leastsubstantially vertical and outside of the vertical trajectory of thecounterweight (103).

The retractable stop disclosed herein may have a wide range ofindustrial, commercial or household applications. The stop may beemployed with new elevator installations or conveniently installed inexisting elevator systems without significant modifications thereto.Moreover, the disclosed stop meets the minimum clearance standard byachieving a smaller overall lateral profile without sacrificingdurability or structural rigidity.

While only certain embodiments have been set forth, alternativeembodiments and various modifications will be apparent from the abovedescriptions to those skilled in the art. These and other alternativesare considered equivalents and within the spirit and scope of thisdisclosure.

What is claimed is:
 1. An elevator retractable stop retractable from adeployed position to a retracted position comprising: a mounting bracketmounted in a vertical orientation, the vertical orientationcorresponding to a direction of motion of a counterweight, the mountingbracket having upper and lower portions; an impact plate having proximaland distal portions, the proximal portion of the impact plate beingpivotably connected to the mounting bracket; and a support member havingan upper end pivotably connected to the distal portion of the impactplate and a lower end movable in relation to the mounting bracket;wherein the proximal portion of the impact plate is pivotably connectedto the upper portion of the mounting bracket, and the impact plate ishorizontal in the deployed position to block downward movement of thecounterweight and is vertical in the retracted position, whereinhorizontal is perpendicular to vertical; and wherein the support memberremains vertical both in the deployed position and the retractedposition.
 2. The retractable stop of claim 1, further comprising a crossmember having a proximal end pivotably connected to the mounting bracketand a distal end pivotably connected to the support member.
 3. Theretractable stop of claim 2, wherein the cross member is horizontal inthe deployed position.
 4. The retractable stop of claim 2, wherein thecross member is vertical in the retracted position.
 5. The retractablestop of claim 1, wherein the mounting bracket is secured to a car guideof an elevator assembly.
 6. The retractable stop of claim 5, wherein themounting bracket is in direct contact with a pit floor of the elevatorassembly.
 7. The retractable stop of claim 5, wherein a verticaltrajectory of the counterweight is blocked by the impact plate when thestop is in the deployed position.
 8. The retractable stop of claim 5,wherein a vertical trajectory of the counterweight is not blocked by theimpact plate when the retractable stop is in the retracted position. 9.The retractable stop of claim 1, wherein the mounting bracket comprisesa holding member that releasably couples the mounting bracket andsupport member together when the stop is in the retracted position. 10.The retractable stop of claim 9, wherein the holding member comprises aretractable locking pin capable of protruding into a receiving area onthe support member when the stop is in the retracted position.
 11. Theretractable stop of claim 10, wherein the locking pin is actuated by asolenoid.